Bring 1 cup of water to a boil in a medium saucepan.
Combine salt and cornmeal. Add slowly to the boiling water, stirring constantly to prevent lumps. Add the butter and stir to blend. Remove the pan from the heat; transfer to a mixing bowl and let it cool to lukewarm.
Combine vinegar and milk and let it stand for 5 minutes.
Add 1 1/2 cup of milk mixture to cornmeal mixture; blend well.
Add eggs and stir to blend.
Dissolve the baking soda in the remaining 1/2 cup of the milk mixture and then add it to the cornmeal mixture; stir until well blended.
Pour the batter into a greased 1 1/2-quart casserole. Bake at for about 30 minutes.